Positive correlation between plasma nitrite and performance during high-intensive exercise but not oxidative stress...

Several studies suggest that exercise is associated with elevated oxidative stress which diminishes NO bioavailability. The aim of the present study was to investigate a potential link between NO synthesis and bioavailability and oxidative stress in the circulation of subjects performing high-intensive endurance exercise. Twenty-two male healthy subjects cycled at 80% of their maximal workload. Cubital venous blood was taken before, during and after exercise, and heparinized plasma was generated. Plasma concentrations of nitrite and nitrate were quantified by GC-MS and of the oxidative stress biomarker 15(S)-8-iso-PGF(2alpha) by GC-MS/MS. pH and pCO(2) fell and HbO(2) increased upon exercise. The duration of the 80% phase (d80) was 740+/-210s. Subjects cycled at 89.2+/-3.3% of their peak oxygen uptake. Plasma concentration of nitrite (P<0.01) and 15(S)-8-iso-PGF(2alpha) (P<0.05) decreased significantly during exercise. At the end of exercise, plasma nitrite concentration correlated positively with d80 and performed work (w80) (each P<0.05). Changes in nitrate concentration also correlated positively with d80 (P<0.05) and w80/kg (P<0.01). These findings provide evidence of a favorable effect of nitrite on high-intensive endurance exercise. The lack of association between 15(S)-8-iso-PGF(2alpha) and NO bioavailability (nitrite concentration) and NO biosynthesis (nitrate concentration) suggest that oxidative stress, notably lipid peroxidation, is not linked to the l-arginine/NO pathway in healthy male subjects being on endurance exercise.